### Abstract

We show that in the model of zero error communication complexity, direct sum fails for average communication complexity as well as for external information cost. Our example also refutes a version of a conjecture by Braverman et al. that in the zero error case amortized communication complexity equals external information cost. In our examples the underlying distributions do not have full support. One interpretation of a distributions of non full support is as a promise given to the players (the players have a guarantee on their inputs). This brings up the issue of promise versus non-promise problems in this context.

Original language | English (US) |
---|---|

Title of host publication | ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science |

Publisher | Association for Computing Machinery |

Pages | 517-522 |

Number of pages | 6 |

ISBN (Print) | 9781450322430 |

DOIs | |

State | Published - Jan 1 2014 |

Externally published | Yes |

Event | 2014 5th Conference on Innovations in Theoretical Computer Science, ITCS 2014 - Princeton, NJ, United States Duration: Jan 12 2014 → Jan 14 2014 |

### Publication series

Name | ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science |
---|

### Other

Other | 2014 5th Conference on Innovations in Theoretical Computer Science, ITCS 2014 |
---|---|

Country | United States |

City | Princeton, NJ |

Period | 1/12/14 → 1/14/14 |

### All Science Journal Classification (ASJC) codes

- Computational Theory and Mathematics

## Fingerprint Dive into the research topics of 'Direct sum fails for zero error average communication'. Together they form a unique fingerprint.

## Cite this

*ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science*(pp. 517-522). (ITCS 2014 - Proceedings of the 2014 Conference on Innovations in Theoretical Computer Science). Association for Computing Machinery. https://doi.org/10.1145/2554797.2554844